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Jérôme Martin

Publications and source records attributed to Jérôme Martin.

3 recordsLinked to original sources
PubMed2006

Testing for w < -1 in the solar system.

In scalar-tensor theories of gravity, the equation of state of dark energy, w, can become smaller than -1 without violating any energy condition. The value of w today is tied to the level of deviations from general relativity which, in turn, is constrained by solar system and pulsars timing experiments. The conditions on these local constraints for w to be significantly less than -1 are established. It is demonstrated that this requires us to consider theories that differ from the Jordan-Fierz-Brans-Dicke theory and that involve either a steep coupling function or a steep potential. It is also shown how a robust measurement of w could probe scalar-tensor theories.

Journal Article↗
PubMed2005

Gravity waves at the interface between miscible fluids and at the top of a settling suspension.

Gravity waves were generated at the interface between miscible fluids, or at the top of a settling suspension or a fluidized bed. For these three systems the dispersion relation was measured and compared to the theory and calculated between two buoyant viscous fluids without surface tension. The experimental findings are found to be in good agreement with theory when effective viscosity and volume-averaged density values are used.

Journal Article↗
PubMed2004

On the "Causality argument" in bouncing cosmologies.

We exhibit a situation in which cosmological perturbations of astrophysical relevance propagating through a bounce are affected in a scale-dependent way. Involving only the evolution of a scalar field in a closed universe described by general relativity, the model is consistent with causality. Such a specific counterexample leads to the conclusion that imposing causality is not sufficient to determine the spectrum of perturbations after a bounce provided it is known before. We discuss consequences of this result for string motivated scenarios.

Journal Article↗